I know numerous leaders with great potential. They have all the appearance of being a good leader. But they lack one thing — or two.

In my experience, some of this self-learned the hard way, there are a few killers of good leadership.

I decided to compile a list of some of the most potent killers I’ve observed. Any one of these can squelch good leadership. It’s like a wrecking ball of potential. If not addressed, they may even prove to be fatal.

It’s not that the person can’t continue to lead, but to grow as a leader — to be successful at a higher level or for the long-term — they must address these killers.

Here are 12 killers of good leadership:

Defensiveness – Good leaders don’t wear their feelings on their shoulders. They know other’s opinions matter and aren’t afraid to be challenged. They are confident enough to absorb the wounds intended to help them grow.

Jealousy – A good leader enjoys watching others on the team excel — even willing to help them.

Revenge – The leader that succeeds for the long-term must be forgiving; graceful — knowing that “getting even” only comes back to harm them and the organization.

Fearfulness – A good leader remains committed when no one else is and takes risks no one else will. Others will follow. It is what leaders do.

Favoritism – Good leaders don’t have favorites on the team. They reward for results not partiality.

Small-mindedness – Good leaders think bigger than today. They are dreamers and idea people.

Pridefulness – Pride comes before the fall. Good leaders remain humbled by the position of authority entrusted to them.

Rigidity – There are some things to be rigid about, such as values and vision, but for most issues, the leader must be open to change. Good leaders are welcome new ideas, realizing that most everything can be improved.

Laziness – One can’t be a good leader and not be willing to work hard. In fact, the leader should be willing to be the hardest worker on the team.

Unresponsiveness – Good leaders don’t lead from behind closed doors. They are responsive to the needs and desires of those they attempt to lead. They respond to concerns and questions. They collaborate more than control. Leaders who close themselves off from those they lead will limit the places where others will follow.

Dishonesty – Since character counts highest, a good leader must be above reproach. When a leader fails, he or she must admit their mistake and work towards restoration.

A leader may struggle with one or more of these, but the goal should be to lead “killer-free”. Leader, be honest, which of these wrecking balls do you struggle with most?